In an environment of a ubiquitous network, various heterogeneous networks are integrated for real and cooperate with each other in serving a user. Service-flows processed cooperatively by multiple terminals in multiple networks are associated with, or independent from, each other. Compared with independent service-flows, synchronization between associated service-flows is required. Such synchronization is involved in two processes; one process is of transfer from a service-providing server to an access-network terminal through an access network, wherein the access-network terminal is for example an access-network gateway or another terminal device directly accessing a communication network; the other process is of transmission from each access-network terminal to a destination terminal. Currently, in a research on terminal aggregation based on environmental context projected by the committee on ubiquitous network technology (TC10) of China Communication Standards Association (CCSA), access-network terminals form a virtual terminal and work cooperatively; the access-network terminals in the virtual terminal include a controlling device and member devices, and synchronization will be required in transmitting sub-service-flows downloaded by member devices to the controlling device.
According to prior investigation, synchronization in the two processes is implemented only by the destination terminal of a service, that is, synchronization is implemented by caching a received service-flow in a cache set in the destination terminal, and presenting service packets to the user only after all the service packets are received. Such synchronization implemented on the destination terminal forces a service-flow with a fast processing rate to wait for a service-flow with a slow processing rate, thereby increasing delay and reducing a system throughput while failing to prevent a certain unexpected random event encountered during transmission, such as packet loss in competition, unexpected delay and the like.